Electric meter.



No. 698,673. P atented Apr. 29, I902.

T. DUNCAN.

ELECTRIC METER.

(Application filed Nov. 27, 1899.) (No Model.) 2 Sheets8heet I.

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No. 698,673. Patehted Apr. 29, I902.

. T. DUNCAN.

ELECTRIC METER.

(Application filed Nov. 27, 1899.) (No Model.) 2 Sheets-Sheet 2;

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' ternating-current service than the commu- UNITED STATES THOMAS DUNCAN,OF CHICAGO, ILLINOIS, ASSIGNOR TO THE SIEMENS do I HALSKE ELECTRICCOMPANY OF CORPORATION OF ILLINOIS.

PATENT OFFIC AMERICA, OF CHICAGO, ILLINOIS, A

ELECTRIC METER.

SPECIFICATION forming part of LettersPatent No. 698,673, dated April 29,1902.

Application filed November 27, 1899. Serial No. 738.286. (N0 model.)

To all whom, it ntay concern: 1

Beit known that I, THOMAS DUNCAN, a cit izen of the United States, and aresident of Chicago, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Electric Meters, ofwhich the following is a specification.

The invention relates to improvements in motor-meters for alternatingcurrents, and particularly to the type known in the art as commutatedand contact meters.

The object of the invention is to provide a meter of the commutated typewhose magnetic field that is produced by the armaturewindiugs will beexactlyin phase with the impressed electromotive force. In meters ofthis class or those in which the electromot-ive force is represented bythe shunt windings of the armature it is necessary that the magnetismproduced by the armature should be exactly in phase with theelectromotive force in order to make the readings of the meter correcton inductive loads. Meters with shuntwound armatures must necessarily bewound with a great number of turns, so as to keep the energy consumedaslow as possible when competing with the induction type of motormeters,which are much more efficient for altated type. The many turns of wirewound upon the armature cause the shunt-current which traverses it tolag behind the impressed electromotive force by an amount depending uponthe self-inductive efiect of these turns, and by increasing their number to lessen the energy consumed this self-inductive or lagging effectbecomes very manifest, since it increases at a rate proportional to thesquare of the turns. For this reason it is obvious that some means mustbe employed to neutralize or compensate for the inductance of thearmature-circuit in order that the turns may be increased by anypractical amount to reduce the energy as much as possible or to the sameamount as is consumed in the most modern types of inductionmotor-meters.

In measuring the true watts on inductive loads the meter must have amagnetic field that is coincident in phase with the pressure;

of one hundred per cent, and if the current be caused to lag ninetydegrees behind the pressure the meter will continue to rotate, since thephase difference between the magnetism of the armature and the magnetismof the series coils will only be eighty degrees and would require a lagof one hundred degrees between the impressed electromotive force and thecurrent before the meter would cease to rotate, whereas it ought to stopwhen the angle of lag is ninety degrees.

In the accompanying drawings, which form part of this specification,Figure 1 is a front elevation showing the arrangement of its operativeparts. Fig. 2 is a plan view showing some of the magnetizing or fieldcoils in section. Fig. 3 is a vector diagram showing the phase relationsof the electromotive force, shunt-currents, and the effective magnetismof the armature.

In describing the improvements there is employed a generator ofalternating currents 1, which supplies the translating devices 4. bymeans of leads or wires 2 and 3. Included in circuit with one of thesaid leads are the two series field-coils 13 and 13 and through whichthe current passes that is supplied to the translating devices. Thesecoils set up a magnetic field that is proportional to the current inamperes. A revoluble shuntwound armature 11 is mounted upon a spinple16, which rests upon a step 19 and is held in a vertical position by theupper bearing 20. This armature 11 is wound with many turns of fine wireand having the terminals of its coils connected in any suitable mannerto the commutator 15. The shunt-current supplied to the armature-coilsis taken from the leads 2 and 3 with the wires 8 and 9. To assist inkeeping down the inductance and energy, a noninductive resistance 10isused in series with the armature in the ordinary manner. To supply amagnetic field in phase with the pressure, I employ themagnetizing-coils 12 and 12, whose magnetic axis is coaxial with themagnetic axis of the armature 11 and at right angles to the magneticaxis of the series field-coils 13 and 13. The current through the coilsl2 and 12 is in an opposite direction to that through the armature 11,setting up therebya phase difference of one hundred and eighty degrees.This displacement of phase isfurther augmented by the insertion of animpedance-coil 5 in circuitwith the coils 12 and 12. The coils'12 and 12are supplied with current from the same source as the armature bytheWires 6 and 7. In Fig. 3 the line 0 a, represent the impressed electromotive force; the line 0 Z), the current and magnetism of the. armature11; the line 0 c, the current and magnetism of the magnetizingcoils 12and 12, and the line 0 d the resultant magnetism of the two lines o I)and 00, or the effective magnetism that represents the volts and whichcooperates with the magnetism of the coils 13 and 13 in developing thetorque which sets the armature in motion. The revolutions of thearmature are integrated by the train 14, which may be of any well-knowntype. To make the speed of the armature proportional to the torque andto the watts, any ordinary magneto-electric damping device may beemployed, and here comprises an aluminium disk 17, embraced in itsrevolutions between the poles of the permanent magnets 18 and 18.

The improvement may be applied to other formsof meters which employ ashunt-coil to represent the pressure in volt-s, such as the well-knownforms of oscillating and clock meters or those in which contacts in lieuof a commutator are operated either periodically or by the movements ofthe meter itself,without departing from the scope or spirit of thenvention.

Since the coils 12 and 12 are in eifect the same as one coil which isdivided into two, so as to permit of the spindle being operated in thecenter, I have referred to these coils in the claims as themagnetizingcoil.

I claim 1. In a commutated motor-meter, aseries field-coil, ashunt-wound armature, a magnetizing-coil that is magnetically coaxialwith said armature, and means for integrating the revolutions of saidarmature.

2. In a motor-meter of the class described, a series field coil orcoils, a movable armature, a magnetizing-coil that is magneticallycoaxial with said armature and at right angles to the magnetic axis ofsaid series field coil or coils, and means for integrating therevolutions of said armature. f

3. In a motor-meter of the class described,

a series field-coil, a shunt-wound revoluble armature, a commutator forsaid armature, a

magnetizing coil or coils having the same mag netic axis as saidarmature, the magnetic axes of both the armature and magnetizing coil orcoils at an angle to the magnetic axis of said series field-coil, amagneto-electric damping device, and means for integrating therevolutions of said armature.

4'. In an energy meter of the class described, a series field coil, a'revoluble armature, meansjfo'r conducting current into said armaturefrom the source of pressure, a non-inductive resistance in series withthe armature, a magnetizing-coil receiving current from the same sourceof pressure as said armature, the current of the magnetizing-coil havinga'different time period from the current traversing said armature, andmeans for lagging the current traversing the'magnetizingcoil.

5. In a meter for measuring alternating currents, a series field-coil, ashunt-wound armature, a non-ind u ctive resistance in series with saidarmature, a magnetizing-coil in cooperative relation with said armature,an impedance-coil in series with said magnetizing coil, the magneticaxes ofthe series field and magnetizing coils being at right angles, acontactdevice for conducting current to the armature, a magneto-electricdamping device, and an integrating mechanism responding to therevolutions of the armature.

6. The combination with a meter for alter.-

natingcurrents of a series field-coil, a shunt wound armature having itsmagnetic or polar axis at an angle to the polar axis of said seriesfield-coil, a magnetizing-coilthat is magnetically coaxial with saidarmature, and means for lagging the current traversing saidmagnetizing-coil.

7. In a commutatedmotor'meter, the combination with a commutatedshunt-wound armature, of a field-winding,-and a phasemodifying windingininductive relation with said armature, substantially'as described.

8. In a commutated motor-meter, the combination with acommutatedshunt-wound ar mature, of a field-winding, and aphase-modifying winding in inductive relation with said armature, andconnected in parallel therewith in the Work-circuit, substantially asdescribed.

In testimony that I claim the foregoing as my invention I affix mysignature, in the presence of two subscribing witnesses, this 11th dayof November, A. D. 1899.

THOMAS DUN CAN.

W'itnesses: V

J. W. DALTON, WM. F. MEYER.

